The signatures of the document function in section 16.1 of XSLT 2.0[1] are 

 document($uri-sequence as item()*) as node()*
 document($uri-sequence as item()*, $base-node as node()) as node()*

The first bullet in that section describes the behaviour of the function if an item in $uri-sequence is of type xs:string, xsl:anyURI or xs:untypedAtomic.  It does not indicate what should happen if an item is an atomic value of any other type.  The second bullet indicates that if $uri-sequence is a node, it is atomized, and every item in the atomized sequence MUST be of type xs:string, xsl:anyURI or xs:untypedAtomic.

In XSLT 1.0, if the first argument to the document function was not a node, it was converted to string as if by a call to the string function.[2]  If that was the intended behaviour in the case of an atomic value of a type such as xs:boolean, that needs to be explicitly stated.  If it was intended to be an error, that should be stated as well, and the incompatibility noted in appendix J.1.4.

As for a node whose typed value contains items of types other than the three mentioned, it seems clear that that is expected to be a type error, but the required error code is not mentioned by the second bullet.

[1] http://www.w3.org/TR/xslt20/#document
[2] http://www.w3.org/TR/xslt#function-document